In the bundled instruments, there is a lot of variation in how the trills are being performed. Some are fast, some start slow and speed up. The latter become problematic when writing fast music using short duration trills. It would be great if we could chose between the two as both can be useful. For now, the only work around I can find is writing out the trill as a bunch of fast notes, but that dosesn't really sound the same. This has been an issue for several versions of the software (I've been using Notion since 1.5).